1. Field of the Invention
This invention relates to a process for the prodcution of m-phenoxybenzyl alcohol. More specifically, this invention relates to a process for producing m-phenoxybenzyl alcohol by the reaction of chlorobenzene with m-hydroxybenzyl alcohol.
2. Description of the Prior Art
m-Phenoxybenzyl alcohol is a starting material for pyrethroid-type insecticides. In recent years, there has been an increasing demand for pyrethroid-type agricultural chemicals having low toxicity in order to reduce effects of agricultural chemicals on the human body, and m-phenoxybenzyl alcohol is accordingly in great demand. It is one great problem, therefore, in the development of agricultural chemicals to supply m-phenoxybenzyl alcohol at low costs.
Generally, the prior production of m-phenoxybenzyl alcohol relies on the chlorination or oxidation of the side chain of m-phenoxytoluene. This method, however, has the following defects.
(1) Chlorination of the side chain of m-phenoxytoluene
In the chlorination reaction of the side chain methyl group, a second chlorine addition occurs at the benzyl position to form a by-product. The desired product should therefore be separated and purified, and the hydrolysis in the subsequent step is complex.
(2) Oxidation of the side chain of m-phenoxytoluene
In the oxidation of the side-chain methyl group, the benzyl position is oxidized to the aldehyde or carboxylic acid without the reaction stopping at the stage of the alcohol. The resulting benzaldehyde or benzoic acid must be reduced to the desired product. Furthermore, at the time of oxidation, a large amount of potassium permanganate should be used, and the method is as complex as in (1).
Condensation of an m-chlorobenzoic acid ester or nitrile and a phenolate is also known as a method of producing m-phenoxybenzyl alcohol (French Patent No. 2,456,727). However, the m-chlorobenzoic acid ester or nitrile used in this invention is expensive, and the method cannot be industrially advantageous.
A method of obtaining m-phenoxybenzyl alcohol from m-hydroxybenzyl alcohol and bromobenzene using a copper dust as a catalyst was proposed (Japanese Laid-Open Patent Publication No. 61443/1973). The yield, however, is as low as about 80%. Since bromobenzene is higher in price than chlorobenzene, such a yield is industrially insufficient.